Without knowing many of the specifics related to context it is difficult to identify what exactly might be going on with your daughter. However there are some things to keep in mind in relation to children who are leaving toddlerhood behind.
Like every age, children around the age of 4 present some ups and downs, not least of which can be a seemingly infinite number of ‘why’ questions every day…one study estimated over 500 per day!
On a more serious note it is important to remember that every child is different, but there are some things you can expect at this important age. First, this is a time of marked insecurity which can lead to a great deal of whinging, crying and frequent questioning along with the occasional acts of defiance and cries of ‘I hate you’! This is likely compounded by a new baby in the family.
Your daughter will expect your attention and be jealous of attention given to others…again, very normal behaviours at this age and like other age related behaviours, this too shall pass. In the meantime, the best thing you can do is try to find some one on one time with your daughter.
Perhaps you can schedule a daily and/or weekly activity together when it is just the two of you. You can then use this to help reinforce the behaviours you desire from her and remind your daughter that you love her as you always have; it’s just that you are a bit busier.
Another thing you can do is find things for your daughter to do when you cannot give her the attention she is currently craving…grandparents, play groups and other activities can help. In the end, attention is the key…try to give your daughter some quality one on one attention and find other avenues that can feed that current need. And finally please remember, this is normal behaviour and it will pass.